This invention relates to a control arrangement for a roll carrier for supplying a web as it is unrolled. More particularly, the invention relates to a roll carrier for providing a web with a predetermined tension having an associated electric drive and braking machine having a speed control and means for continuously determining optimized speed control parameter from the system parameters.
Operation of control arrangements for roll carriers with fixed speed control parameters is generally unsatisfactory because the time constant of the system changes within wide limits during an unwinding operation. The time constant changes because the moment of inertia of the winding rapidly decreases with decreasing diameter. In DE-OS No. 27 32 644, continuous determination of optimized control parameters as a function of the changing system parameters is provided for. There the instantaneous moment of inertia is determined by a computer from input quantities for the width of the web, the specific density of the material, and the instantaneous radius of the winding. There, also, the width of the web could be determined by a mechanical measuring device.
It is an object of the present invention to develop the control arrangement for a roll carrier of the type disclosed in DE-OS No. 27 32 644 in such a manner that inputs or measurements of the specific density of the web material and of the web width are no longer necessary.